A social worker at a juvenile prison who gave a youth a key and cellphone for an attempted escape was justifiably sacked, the Employment Relations Authority has ruled.

Joseph Bartram was a qualified residential social worker at the Waimakariri unit of Te Puna Wai o Tuhinapo Residence in Christchurch for six years before his dismissed last October.

Bartram complained to the authority that his dismissal was unjustified and unfair, but authority member Christine Hickey found that his employer, the Ministry of Social Development, was correct in dismissing him.

In her decision released today, Hickey said three young people attempted to escape from the facility on March 30 last year.

One of them was found to have a shift leader's key and ministry cellphone in his possession.

After a ministry investigation, it was determined that Bartram had covertly provided both the items to the youth.

The ministry said closed-circuit television footage showed Bartram giving the youth the key as he handed him a pair of jeans, and later providing him with the cellphone.

The youth used the key to try to escape with two other youths, but they were apprehended before they were able to leave the facility.

Bartram said he had not given the youth either of the items.

The key had not been given with the jeans and the other item was an Easter egg, which he gave to the youth covertly so the other youths in the facility would not see him doing it and clamour for one themselves, he said.

He claimed his dismissal process was unfair.

Hickey said the ministry's investigation was thorough and robust.

"There were some additional investigative steps that may have strengthened the process of investigation, but overall the investigation raised sufficient evidence to support the allegations," she said.

Among other things, the evidence from the youth on when he was given the items was able to be corroborated by the CCTV evidence, she said.

The ministry did not have to prove Bartram's guilt to a criminal standard, although given the serious allegations, it needed to have a convincing level of evidence, she said.

There was sufficient evidence of sufficient weight to conclude that the allegations against Bartram were made out, she said.

"Dismissal was the inevitable consequence because of the security risk inherent in keeping Mr Bartram employed."

The authority did not make the decision lightly as the nature of the dismissal would seriously impinge on Bartram's ability to work as a social worker in the future, Hickey said.